The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Generally, a pedestal heater is a semiconductor processing tool for heating a wafer disposed thereon. The pedestal heater includes a heating plate and a support shaft disposed under the heating plate. The heating plate may include a ceramic substrate and a plurality of resistive heating elements embedded in the ceramic substrate to define a plurality of heating zones. Typically, the same power is applied to the plurality of resistive heating elements at the same ramp rate during heater startup.
Despite the same power applied to the resistive heating elements, some resistive heating elements may be heated faster than the other heating elements due to, for example, the position of the heating zones relative to heat sinks, and differences in the characteristics of the heating zones caused by non-uniform manufacturing. When a heating zone is heated faster than an adjacent heating zone, the temperature difference between the adjacent heating zones causes different thermal expansion and consequently thermal stress between the adjacent heating zones. Significant thermal stress may result in generation of thermal cracks in the ceramic substrate.